The CCS7 (also called Signalling System No. 7) signalling protocol provides a practical method for implementing sophisticated, network-based intelligent services by providing "out-of-band" signalling making use of a separate high-speed data link for call setup and routing. As the demand for network-based intelligent services such as calling number/name delivery, and automatic callback has increased, there was a recognition of the need to increase the traffic capacity and improve load balancing capabilities of the typical CCS7 network.
In response to this need, the standards bodies responsible for setting standards for CCS7 networks (ie. the American National Standards Institute (ANSI) and Bellcore.TM.) have issued requirements to be met by CCS7 network providers to implement the expanded capacity. One of these requirements pertains to expanding the Signalling Link Selector (SLS) field in the routing label of a data packet from a length of 5 bits to a length of 8 bits, thereby enabling the number of links between nodes to increase from 8 to 16, and allowing for improved load sharing among communication links interconnecting the nodes making up a CCS7 network.
However, it is not anticipated that all nodes in a typical CCS7 network will be updated at the same time to support the new requirements. This means that there will be a period when only some nodes in a CCS7 network will functionally support 8-bit SLS, while others will only functionally support 5-bit SLS. With a properly formulated strategy for converting a 5-bit SLS to a 8-bit SLS, many of the benefits of 8-bit SLS will be realized, even though not all of the nodes in the network are capable of functionally supporting 8-bit SLS.